Cache cibuildwheel interpreters and let dependabot update GitHub Actions

Port two CI maintenance changes from the simplification repo:

- Persist CIBW_CACHE_PATH via actions/cache so the per-version CPython
  downloads are reused between builds instead of re-fetched every run.
- Remove the dependabot ignore rule for actions/*, so cross-major bumps
  (which moving major tags do not track) are proposed under the existing
  github-actions group.

Author: urschrei

.github/dependabot.yml

@@ -4,10 +4,6 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
-    ignore:
-      # Optional: Official actions have moving tags like v1;
-      # if you use those, you don't need updates.
-      - dependency-name: "actions/*"
 
   - package-ecosystem: "uv"
     directory: "/"

.github/workflows/wheels.yml

@@ -110,9 +110,16 @@ jobs:
         with:
           version: "latest"
 
+      - name: Cache cibuildwheel interpreters
+        uses: actions/cache@v5
+        with:
+          path: ${{ github.workspace }}/.cibw-cache
+          key: cibw-${{ matrix.id }}-${{ hashFiles('.github/workflows/wheels.yml') }}
+
       - name: Build and Test Wheels
         uses: pypa/cibuildwheel@v3.4.1
         env:
+          CIBW_CACHE_PATH: ${{ github.workspace }}/.cibw-cache
           CIBW_BUILD: ${{ matrix.pybuilds }}
           CIBW_ARCHS_MACOS: ${{ matrix.arch }}
           CIBW_ARCHS_LINUX: ${{ matrix.arch }}